Sound amplifier



Nov. 11, 1930. T. LINDENBERG 1,781,465

SOUND AMPLIFIER Filed Jan. 19, 1927 Patented Nov. 11, 1930 PATENT OFFICE" I THEODORE LINDENIBERG, OF COLUMBUS, OHIO soUNn AMPLIFIER Application filed January 19, .1927.

This invention relates to improvements in sound amplifiers and more particularly to amplifiers of the type employed in connection with talking machines, radio receiving apparatus, telephonic receivers and other sound reproducing apparatus where the sound is recreated either through electrically or mechanically vibrated diaphragms.

In accordance with the present invention a sound amplifier is provided which is formed to include a plurality of closely spaced vibratory plates, held in clamped assembled relationship and provided with axially aligned openings constituting a sound con duit, the inlet end of the latter being registered with a sound reproducer, whereby the sound travelling through the conduit from the inlet to the outlet ends thereof is amplified in volume and its total properties improved by the sympathetic vibration of the numerous plates of which the amplifier is chiefly composed.

Another object of the invention resides in forming the plate from materials pos- 2 sessing dilferent resonating properties, such as metal, wood, paper, composition materials and the like, with the view of developing more completely the fundamental sounds and overtones present in the reproduction, and to bring out more fully and distinctly in true relative proportions the various tone shadings and modulations of complex sounds such for example as those developed by orchestral renditions, wherein numerous instruments are employed.

lVith these and other objects in view, as will appear as the description proceeds, the invention consists in the novel features of construction, combinations of elements and arrangements of parts hereinafter to be fully described and pointed out in the appended claims.

In the accompanying drawing:

Figure 1 is a view in side elevation and partly in vertical section of an amplifier constructed in accordance with the features of the present invention,

Figure 2 is a top plan View thereof,

Figure 3 is an enlarged detail vertical sec- Serial No, 162,153.

tional view taken on the line 33 of Figure2.

Referring more particularly to the drawing, the numeral 1 designates'the improved amplifier comprising the present invention in its entirety. In the particular form of the invention herein selected for illustration the said amplifier is formed to comprise a plurality of thin sheet plates arranged, as shown in Figure 1, in closely spaced relationship and in substantially parallel order and occupying planes perpendicular to the major axis of the amplifier. These plates are designated by the numeral 2 and are of substantially identical construction, each being provided with an axial opening whereby when the plates are in assembled relationship these openings are aligned to constitute a sound conduit, designated by the numeral 3. In this instance the conduit is of outwardly tapering form, being of smaller diameter at its sound inlet end and of larger diameter at the sound outlet end. Connected in any suitable manner with the inlet end of the conduit is a sound reproducer 4:, which, in the case of a radio amplifier, is .of the usual electrically excited type involving the usual diaphragm and magnetic field, (not shown) but it will be understood that the amplifier may be incorporated in talking machines wherein a purely mechanically operated sound reproducer is'utilized; NVhile the conduit 3 has been shown to taper outwardly 'yet, if desired, this conduit may be of uniform diameter throughout its length if such a construction is found desirable.

,In this instance the plates are of substantially square or rectangular form and are provided at their corners with registering openings 5, through which passes a plurality ofrtie bolts 6, having their threaded ends equipped with binding nuts 7. Spacing washers 8 are carried by the bolts and located between the plates 2 to maintain the latter in.

proper relationship. These washers may be formed from rubber, metal or other suitable I material so that by tightly binding or clamping the plates in their operative positions, vibratory control thereof is effectively secured and uncontrolled vibrations avoided.

I have found it desirable to form the plates of different materials, such as thin sheet brass, wood, heavy paper, leather, and other resonant materials which possess varying resonance. By virtue of this construction in each amplifier sound waves passing through the conduit and the vibratory air column therein set up in direct vibration on the part of the plates 2 which because of the relatively great surface thereof provided in the total number of plates result in amplifying and clearing the quality and volume of the sound after it leaves 7 proportions complex sounds which are reproductions of, for example, orchestral renditions so that the notes produced by these diff'erent instruments may be distinctly heard, in their 'proper relationship to the true volume of the totalsounds thus developed. If desired the plates, maybe surrounded with a casing 9 of any suitable material, or the casing may be omitted entirely. w

The spacing of the plates 2* gradually increasing toward the outlet of the amplifier as the sound Waves are increased proportionately in length fromthe inlet end of the amplifier unit. a

Whatv is claimed is:

l. A sound amplifier comprising a plurality of closely spaced vibratory plates arranged transversely With respect to the longitudinal axis of the amplifiensaidplates being provided with centrally disposed openings constitut-ing jointly a sound conduit, said plates being formed from materials possessing dif ferent' resonance, and securing means for mounted for independent vibration upon said base, said plates being provided with centrally disposed openings constituting jointly a sound conduit, said plates being provided at their corners with registering openings, tie rods extending through said openings and connected with said base, spacing Washers carried by said rods and located between said plates, and means located exteriorly of said amplifier for clamping the plates in their operativepositionupon said base.

In testimony whereof I afiix my signature.

THEODORE LINDEN BERG.

clamping said plates .in assembled relationship.

2. A sound amplifier comprising a supporting frame, a plurality of closely spaced vibratory plates of uniform size mounted for independent vibration upon said frame, said plates being provided with centrally disposed openings constituting jointly an outwardly taperingsound conduit, spacers of varying thickness interposed between said plates and so arranged that the spacing between the adjacent plates gradually increases away from the inlet end of the amplifier, and means fors'i'multaneously clamping the plates in their operative positions.

3; A sound amplifier comprising a base," i

a plurality of'closely arranged substantially i. rectangular vibratory platesof uniform size 

